shharma-vipin

public ArrayList<ArrayList<Integer>> pathSum(TreeNode A, int B) {
        
        if(A == null) return null;
        ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
        Deque<TreeNode> deque = new ArrayDeque();
        doItNow(A,B,deque,res);
        return res;
    }
    
    private void doItNow(TreeNode n, int m, Deque<TreeNode> deque,ArrayList<ArrayList<Integer>> res){

shharma-vipin

private boolean checkIt(TreeNode A, TreeNode B){
        if(A == null && B == null) return true;
        
        if(A == null || B == null) return false;
        
        return (A.val == B.val && checkIt(A.left,B.left) && checkIt(A.right,B.right));
    }

shharma-vipin

 public int minDepth(TreeNode A) {
        
        if(A== null){
            return 0;
        }
        
        if(A.left == null && A.right == null){
            return 1;
        }
        

shharma-vipin

public int maxDepth(TreeNode A) {
        if(A == null) return 0;
        int left = maxDepth(A.left);
        int right = maxDepth(A.right);
        return Math.max(left,right)+1;
    }

shharma-vipin

 public ArrayList<ArrayList<Integer>> zigzagLevelOrder(TreeNode A) {
        
        Queue<TreeNode> q = new LinkedList<>();
        if(A == null) return null;
        
        Stack<TreeNode> currentLevel = new Stack<>();
        Stack<TreeNode> nextLevel = new Stack<>();
        
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        currentLevel.push(A);

shharma-vipin

public ArrayList<Integer> postorderTraversal(TreeNode A) {
        
        Stack<TreeNode> s1 = new Stack<>();
        Stack<TreeNode> s2 = new Stack<>();
        
        if(A == null){
            return null;
        }
        
        s1.push(A);

shharma-vipin

 public ArrayList<Integer> preorderTraversal(TreeNode A) {
        
        if(A == null) return null;
        Stack<TreeNode> stack = new Stack<TreeNode>();
        ArrayList<Integer> result = new ArrayList<Integer>();
        stack.push(A);
        
        while(!stack.isEmpty()){
            TreeNode temp = stack.pop();
            result.add(temp.val);

shharma-vipin

public ArrayList<Integer> inorderTraversal(TreeNode A) {
        
        Stack<TreeNode> stack = new Stack();
        TreeNode current = A;
        ArrayList<Integer> result = new ArrayList<Integer>();
         while(current != null || !stack.isEmpty()){
             while(current != null){
                 stack.push(current);
                 current = current.left;
             }

shharma-vipin

public List<Integer> findMaxNumberInGivenSubArray(List<Intger> inputArray, int k){
  
  Deque<Integer> deque = new LinkedList<>();
  List<Integer> ouputArray = new ArrayList<>();
   int i =0;
     for(; i < k; i++){
       while(!deque.isEmpty() && inputArray.get(deque.peekLast()) < inputArray.get(i)){
           deque.removeLast();
       }
       dequeu.putLast(i);